1. Field of the Invention
The present invention relates to a method for mounting a wafer, wherein a plurality of semiconductor devices are provided on the center portion of the major surface, and a wafer, wherein a ring-like reinforcing section is provided, is mounted on the periphery of the major surface with a holding tape. In particularly, the present invention relates to a method for manufacturing a semiconductor device wherein a holding tape can be adhered to the steps of the ring-like reinforcing section without air bubbles.
2. Background Art
In LSI, the densification of packages by three-dimensional mounting or the like is performed, and wafer thinning to approximately 10 μm when the process is completed has been carried out.
In addition, power devises such as IGBT (Insulated Gate-type Bipolar Transistor), or MOSFET (MOS-type Field Effect Transistors) have been broadly used as semiconductor switches in inverter circuits for industry motors, automobile motors, or the like; power supply power sections for high capacitor server; uninterruptible power-supply system or the like. In the fabrication of power devices, for improving power distribution characteristics such as ON characteristics, semiconductor substrate is thinly processed.
In recent years, in order to improve costs and characteristics, semiconductor devices have been fabricated using ultrathin wafers thinned to approximately 50 μm by an FZ (Floating Zone) method.
In general, for thinning wafer, mechanical grinding by back grinding or polishing, and wet etching or dry etching for removing fabricate strains generated by mechanical grinding are performed. Thereafter, a diffused layer is formed on the back surface side using ion implantation or heat treatment, and an electrode is formed using a spattering method or the like.
In such situations, the frequency of wafer cracking in the back face processing is elevated. Therefore, processing methods to make only the center portions thin while remaining the thick outer peripheral as a circularly reinforcing section (lib) have been proposed (for example, refer to Japanese Patent Application Laid-Open No. 2007-19379). By using such wafers having fibs, the warpage of the wafers is substantially reduced, and the transportation of wafers is facilitated. At the same time, the intensity of wafers becomes highly improved, and the breaking or cracking of wafers can be reduced.
When chips are cut to individual pieces, after mounting a wafer in a dicing frame using a holding tape, dicing is performed by blading or using laser. At this time, if the holding sheet is not perfectly adhered, the chips are scattered during dicing, and due to the scattered chips, the production of the semiconductor device becomes difficult.
In order to solve such problems, there has been proposed a method for improving the adherence to the steps by pressing and deforming the holding tape to meet the shape of the lib-having wafer by a precisely adjusted ring-like convex to meet the inner diameter of the circularly reinforcing section (for example, refer to Japanese Patent Application Laid-Open No. 2008-42016). In addition, a method for improving the adherence to the steps by pressing and deforming the holding tape by introducing compressed air has been proposed (for example, refer to Japanese Patent Application Laid-Open No. 2010-118584).